Common Name: Honey Locust, Thorny Locust

Description:
This central North American native is a common ornamental shade tree in the suburbs of America. But this member of the Legume family is gaining popularity in the Permaculture world due to its many uses. It fixes nitrogen in the soil, grows fast, has edible pods commonly used as livestock fodder, provides nectar to beneficial insects, creates high quality lumber which resists rot, and can be used in barren, maritime, drought, and/or polluted lands. This is a truly multi-purpose tree and one that should be considered by every Permaculturist.

Gleditsia triacanthos

History:
Native and widespread in central North America. It was used by Native Americans as a supplementary food source. It has been used in more recent times as a fast-growing, ornamental, shade tree, and thornless varieties have been developed. It has been naturalized in most of eastern North America and it has been introduced to India, South Africa, New Zealand, and Australia. Some consider it a weed tree in these locations.

Trivia:

The name “Honey” likely comes from the sweet flavor of the young pods, because while honeybees to visit this tree, it is not a major source of nectar for them

The inermis variety of Honey Locust is sterile, non-fruiting, and thornless.

In the past, the thorns were used as nails!

The flowers are strongly scented.

The pods mature in late Autumn to Winter and are a great fodder source

Mature pods on the tree. Immature pods are edible to humans.

Honey Locust produces a high quality wood.

USING THIS PLANT

Primary Uses:

Ornamental Tree – The “improved” varieties have been developed for fast-growing, ornamental, shade trees.

Nitrogen Fixing Plant – There is some debate (due to Honey Locust not forming root nodules), but it appears that this tree produces an excess of nitrogen which can be used by surrounding plants. It may come from the roots as recent research at Yale suggests, or it may come from leaf fall and not the roots, but scientists are still studying this.

Edible Pods – The young pods have a pulp that is sweet. The pods can be eaten raw or cooked. A sugar can be made from the pulp. The pulp can be fermented into a beer… I have got to try this!

Edible Seeds – They very young seeds can be eaten raw or cooked. Reportedly taste like peas. Can even be roasted, ground, and used as a coffee substitute.

Biomass Plant – Produces a large amount of leaf fall every year, and it if fast growing… great for rebuilding the soil

Drought Tolerant – once established

Pollution Tolerant – used to reclaim land from mining areas and used in cities with poor air quality

Maritime Plant – tolerates salty conditions

Yield: Not a classic fruit plant, so no yield data can be found.Harvesting: Pods start forming in late Summer and into early Autumn. The pods mature in late Autumn and early Winter.Storage: If the pods or seeds are for human consumption, then they are best used fresh… although no good information is available.

DESIGNING WITH THIS PLANT

Plant Type: Large TreeLeaf Type: DeciduousForest Garden Use: Canopy LayerCultivars/Varieties: There are a number of varieties available, but almost all have been developed for ornamental purposes.

Pollination: Honey Locusts are considered “Polygamo-Dioecious”. This means that there are both male and female trees. The male flowers are not required for pod formation, but are required for full seed development. Pollinated by insects.Flowering: Late Spring to Early Summer.

Life Span:

Years to Begin Bearing: 10 years

Years Between Major Crops: 2 years on average

Estimated Useful Life: Since this tree is often used as a nitrogen-fixing, “nurse” tree to other more desired fruit or nut trees, Honey Locusts are typically not kept around long by Permaculturists… unless the tree is to be used as a fodder source for livestock. Honey Locusts will live to be about 120 years, but can live to 150 years. It is considered a short-lived tree.

Flower buds just forming.

Honey Locust has highly fragrant flowers.

PHYSICAL CHARACTERISTICS OF THIS PLANT

Size: 50-100 feet (15-30 meters) tall and wide; some specimens can be largerRoots: All will have a fibrous component to them, but they also have a deep tap-root… some may have a number of thick, deep roots instead of a single tap-rootGrowth Rate: Fast

Some wild Honey Locust only have a few thorns.

…and some are covered in thorns… there is a reason the thornless varieties are so popular!

GROWING CONDITIONS FOR THIS PLANT

Light: Prefers full sunShade: Does not like shadeMoisture: Dry to wet soils. Can tolerate a wide variety of soil moisture.pH: prefers 6.1-7.5 (but tolerates a wide range of soil conditions)

Special Considerations for Growing:

Honey Locust tolerates juglone (natural growth inhibitor produced by Black Walnut and its relatives). Consider using this tree as a buffer between your walnuts and other plantings.

May need to be protected from rabbits and deer who like to eat the thin bark of young trees

Individual trees may occasionally be hit hard with pests and disease, but are considerably more susceptible when planted in large groups… basically, like with many things in nature, monocrops should be avoided.

Propagation:
From seed – should be soaked in warm water until swollen (usually about 24 hours), and it may need to be filed a bit before soaking. After swelling, the seed is planted and should germinate within a month.

Maintenance:Minimal.

Concerns:

The thorns on this tree can be quite large!

Some people consider this tree to be invasive, so be careful if you are introducing it outside of its natural range

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8 Comments

The Honey Locust tree was first written about in J. Russell Smith’s book Tree Crops: A Permanent Agriculture. The seed pods are full of sugar and some varieties like milkwood and Calhoun have up to 40% protein. This crop is exceptional for animal feed. An 8 inch seedling has a taproot of 40 inches. A 5 year old tree can produce close to 60 lbs of pods per year.
This tree is excellent to establish savanna mimics, food forest and more. We are using this tree to help us slow down rapid succession after clear cut on mountain sides.
Other trees to consider are mesquite and carob.

Nice job of putting together this summary. We use them in our 5 acre forest garden on a 1/3 honeylocust 2/3 fruit tree basis. We space them as a dwarf fruit tree (8feet x 12feet) by training the branches downwards and use them as a live post to hold up our overhead irrigation lines. We also run our vines on them (grape, kiwi, cucumber, beans and peas). Truly a multi-use tree.

Good article. I have an overabundance of the thorned variety of honey locust at my 13 acre farm in North Texas. I am happy that there is some value, but the thorns are the biggest thorn in my side, and in my vehicle tires. I have been able to reduce the tire damage by very carefully harvesting thorns when clearing with chainsaw. I run everything that is not firewood sized through a wood chipper. The thorns sometimes make it through the chipper unscathed, but it is worth it to harvest that material as chips.

From a coppicing perspective, after cutting a honey locust tree to the ground, they reliably sprout multiple thorned rapidly growing branches. You could definitely coppice annually, but the only value I can see for the thinner branches is possibly firewood. I have found that my honey locust firewood degrades a bit faster than some of the other wood we have been collecting, and should be harvested first from the wood pile.

Another thorny native tree I have to deal with is the bois d’arc (horse apple, osage orange), but those thorns don’t cause the vehicle tire problems like honey locust. I was just reminded of them when thinking about managing branch piles and the “joy” associated with shoving thorny branches through a wood chipper.

On the subject of nitrogen fixing, since honey locust acts as a pioneer plant, the argument would seem to be that any plant that can establish a foothold on generally non-fertile ground should immediately be suspected of being able to fix nitrogen, as it makes its own fertilizer.